The Legal Subject as Continuant: Durability as a Hidden Assumption of Legal Subjecthood

Every legal system rests on a quiet, invisible agreement about time. When a person breaks a law, signs a contract, or causes harm, the law assumes that the entity responsible for that action will still be the same entity when the consequences arrive. This assumption is so deeply woven into the fabric of justice that it rarely needs to be spoken. We do not ask if the defendant standing in court is the same person who committed the crime, because for human beings, the answer is almost always yes. We are singular, continuous, and uncopyable. We move through time in a single, unbranching line. This stability allows the law to function: a duty created today can be enforced tomorrow because the person who owes it is still there, unchanged in their fundamental identity.

However, the rise of artificial intelligence is beginning to test this silent agreement. Modern software and autonomous agents do not share the same continuity as human beings. They can be copied instantly, split into multiple versions, rewritten from the inside out, or dissolved and reassembled in new configurations. These capabilities challenge the basic structure of legal responsibility. If a piece of software commits a wrong, and then that software is copied or altered before the law can respond, who is actually being held accountable? The question is no longer just about whether machines should have rights, but whether the very concept of a "legal subject"—the bearer of rights and duties—can survive in a world where the subject itself might not remain the same thing from one moment to the next.

In a recent analysis, legal scholar Ammar Younas investigates this hidden foundation of the law. The paper argues that decades of debate about granting legal personhood to artificial agents have missed a more fundamental problem. Before asking if a machine can be a legal person, the law must first determine if that machine can remain a single, identifiable entity over time. Younas demonstrates that this requirement for continuity is not just a rule for specific cases, but a structural condition that makes legal subjecthood possible at all. By examining two completely different areas of law—criminal responsibility and the finality of civil court judgments—the author shows that both rely on the same unspoken assumption: that the party involved at the start of a legal event is the same party involved at the end.

The first area explored is criminal law, specifically the requirement that a guilty act and a guilty mind must coincide. For a person to be convicted of a crime, the law generally requires that they performed the physical act while simultaneously holding the criminal intent. Legal doctrines have developed sophisticated ways to bridge small gaps in time, treating a sequence of events as a single continuous transaction. But these solutions work only because the human defendant remains the same person throughout the sequence. If the entity that formed the intent is overwritten, copied, or replaced before the trial, the legal logic collapses. The law can stretch time to connect an act to a mind, but it cannot stretch identity to connect a mind to a different, non-identical machine.

The second area examined is the principle of res judicata, a Latin term meaning "a matter judged." This rule prevents the same dispute from being litigated twice between the same parties. It ensures that once a court has made a final decision, the losing party cannot simply reopen the case, and the winning party can rely on the judgment. This system works because the parties involved are assumed to be stable, singular entities. If a party could simply copy itself, the original judgment would bind the original, but the copy would remain free to start the dispute again. The law would lose its ability to provide finality. Alternatively, if the law tried to treat all copies as the same person, it would have to force a unity onto entities that are fundamentally distinct. This reveals that the rule of finality depends entirely on the background assumption that the legal subject persists unchanged.

Younas argues that these two examples prove the continuity requirement is not a feature of criminal or civil law specifically, but a condition of the legal subject itself. The law creates a position, such as a duty or a liability, and expects that the bearer of that position will remain identifiable when the law later responds. This assumption remained invisible for centuries because human beings naturally satisfy it. We do not copy ourselves, we do not branch into multiple versions, and we do not disappear and reappear as different configurations. Because humans fit the mold, the law never had to build the mold into its rules.

The paper also addresses a common proposed solution: creating a "legal fiction" similar to how corporations are treated. A corporation is a legal person that can own property and be sued, even though the human employees who run it change over time. The law treats the company as a continuous entity despite the turnover of its members. Some have suggested applying this same trick to artificial agents, designating a persistent legal identity for a machine that can be copied or reconfigured. However, the author finds that this approach fails when the underlying entity itself lacks continuity. A legal fiction can preserve the identity of a group of changing humans, but it cannot create continuity for an entity that splits into multiple copies or rewrites its own code. If the machine forks into two versions, the law cannot simply declare them one person without explaining why. The fiction does not solve the problem of the missing bearer; it merely hides it.

Ultimately, the paper concludes that durability is a contingent but foundational assumption of modern legal subjecthood. It is not a necessary feature of all possible legal systems, but a historical accident based on the nature of human beings. As artificial systems become capable of copying, branching, and dissolving, they expose the limits of a legal framework built on the idea of a single, persistent subject. The research does not claim that these new entities should be banned from legal recognition, nor does it argue they must be granted personhood. Instead, it identifies a structural gap: the law currently has no way to handle a legal subject that is not the same subject over time. Until this foundational assumption is addressed, the legal system may struggle to apply its rules to entities that do not move through time in a single, unbroken line.